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Improving power plant performance through calibration

Author : M Babb

05 September 2009

Calibration helps a power plant to maintain and improve safety, as well as to meet national and international standards. However, calibration is also a matter of profitability. By using high-accuracy calibration equipment, the accuracy of vital measurements can be maintained at required levels and plants can increase their annual power production capability.

Calibration in the utility industries

Instrumentation is used to measure energy flow within power and energy operations in order to monitor and improve operations. While these instruments are not directly used for billing purposes, their proper operation is often key to identifying and preventing energy losses that can have large economic consequences. Failure to properly calibrate these instruments can lead to significant economic consequences.

Instruments typically calibrated in power plants include transmitters, switches, gauges, transducers, frequency devices, and pulse counters. Failure to properly calibrate these devices can significantly affect process operation. Calibrating instruments properly in a timely manner is an important aspect of ensuring the environmental integrity of the process that can reduce the number and severity of environmental issues.

Increasing productivity and safetyAccurate measurements can allow increased energy production. For instance, reducing the measurement uncertainty in a nuclear power plant can potentially increase electrical production up to nearly 2 per cent (see CNA case story).

The economic consequence of this seemingly small power increase typically increases revenues by many millions of euros because the total value of power and energy flows can easily be over a billion euros per year. Small measurement errors caused by poor calibration techniques can potentially result in major revenue losses. Plants are also required to maintain calibration equipment traceable to national and international standards, such as NIST, ISO 9001 and ISO 17025.

Safety is based upon never exceeding established operating limits such as reactor power and cooling capacity. A by-product of improved calibration is an improvement in safety. There are fewer problems because instruments periodically calibrated to more accurate standards reduce the risk associated with these measurements. In addition, improved calibration standards can be used to detect instrument degradation sooner.

Power and energy industry calibrationField calibration allows the in-situ calibration of instruments that measure electrical parameters such as voltage, current, and power—some of which may be used for billing purposes in a power plant. The performance of natural gas and oil flow measurement systems can also influence billing.

In particular, the calibration of flowmeters used to check the custody transfer flowmeters is important. Small variations between these flowmeters can result in large billing differences and could indicate a problem with the custody transfer flowmeter. Field calibrators allow these calibrations to be performed accurately and more efficiently, especially when the instrument is installed in difficult locations, with poor personnel access.

Many electricity, steam, cogeneration, ethanol, bio-diesel, refinery, and other types of energy plants use these measurements to develop process heat and material balances that describe their processes. Heat and material balances can be instrumental in locating opportunities that can save millions of euros of energy.

For example, increased steam flow to a heat exchanger indicates that either the steam trap is leaking, wasting steam, or that the process changed and needs to be investigated to reduce steam consumption. Field calibrators help ensure that these instruments operate properly and accurately, quantifying energy savings.

Automating the calibration processPortable calibrators improve the process by automating the generation of the transmitter inputs and the recording the measurements, making the process less time-consuming and reducing the probability of human error.

Expensive qualification requirements often preclude the opening of transmitters in nuclear power plants. In these applications, the calibration process can be performed faster and more accurately with an automated calibrator as compared to manual calibration techniques.

Beamex calibrators and calibration software form an integrated, automated calibration system. Calibrations performed using automated field calibrators and calibration software with electronic documentation, result in more uniform calibrations that are less prone to human error. The integrated system allows uploads to a PC to produce an instrument database and calibration certificates. With the database, maintenance personnel have the ability to search for instruments due for calibration.

CASE STUDY: Central Nuclear de Almaraz (CNA), Spain

Increasing annual production with high-accuracy calibratorsEnhanced calibration equipment performance makes it possible to perform calibration operations with better uncertainty levels, with which it is possible to improve production results. This is achieved by using the Beamex® MC5 high-accuracy multifunction calibrators for calibration in the power plant.

Improving the measurement of the parameters associated with the determination of reactor power from 2% to 0.4% enabled the power in each unit to be increased by 1.6%. This has a very significant effect on the annual production. (Read complete case story at: http://www.beamex.com/success)